Lubricating oil additive compatibility improver



Patented Mar. 31, 1959 LUBRICATING OIL ADDITIVE COMPATIBILITY IMPROVER Adlai E. Mlchaels, Crawford, and Niilo V. Halrala, Westtield, NJ, asslgnors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Original application May 1,1952,- Serial No, 285,531. Divided and this application October 24, 1955, Serial No. 542,487 1 5 Claims; (CI. 25242.7) I

This invention relates to methods of preparing improved lubricating oil compositions containing different additives having some degree of incompatibility. More particularly, it relates to methods of improving the compatibility if metallo-organic additives and polymeric additive ma- ,terials in lubricating oil compositions. It relates also to' lubricating compositions containing different additive materials exhibiting some degree of incompatibilty to which have been added compounds which will be designated "compatibility improvers.

Lubricating oils manufactured by conventional methods are often unsuited for use under conditions encountered in internal combustion engines and for diverse industrial purposes. Satisfactory lubricating can be generally given by almost any type of lubricant of the properviscosity ifor'brief periods of time. However, fora sustained serv- 2 ice under normal operating conditions the quality of 1ubricants becomes important and it is necessary for the i lubricant not only to carry out the primary functions but also to exhibit the following advantages: (1 the lubricant should operate satisfactorily over a wide temperature range and (2) the deleterious effects of excessive engine deposits should be countered. In'order to achieve these jperiormance objectives; important characteristics of lubricating oils must be enhanced, especially viscosity, viscosity index, pour point and ability to remove carbonaceous deposits. To obtain these and other desirable re-' sults, various additive materials have been blended with lubricating oils to extend the quality of lubricants for specific purposes beyond the level which can be reached by known manufacturing methods.

Generally, additives have been developed for specific purposes, for example, pour point depressants, viscosity index improvers, sludge dispersers, detergents, and the like. To obtain a general purpose lubricant having a high level of performance with respect to pour point, viscosity index, sludge dispersion, and the like, it is necessary to incorporate in the lubricating oil base stock many varied additive materials. Because of the diversed nature of many of these materials, it is not surprising that a certain incompatibility among them exists. For example, metallo-organic compounds used as detergent additives are frequently incompatible with high molecular weight polymeric materials used primarily as thickeners, vis cosity index improvers, pour point depres'sors, etc. Lubricating oils having incorporated therein the above-mentioned additive materials are frequently unacceptable because of turbidity. It has'also been found that certain of the metallo-organic additive materials actually reduce the effectiveness of certain of the polymeric addition agents. For instance, it has been found that the pour point depressing potency of some of the additive materials is markedly reduced when blended with a metallo-organic iludge dispersing agent in an oil base.

It has now been discovered that the addition of certain unacceptable turbidity of a lubricant using the two additives. It has also been found that the undesirable depreciation of pour point depressing potency is removed by the incorporation into the blend of these oxygenated organic compounds.

These oxygenated organic compounds may be represented by the formula:

where R is an alkyl group having 1 to 8 carbon atoms, R is hydrogen or an alkyl group having 1 to 8 carbon atoms, and n is an integer from 1 to 8.

Among the operable oxygenated compounds covered by the formula above are the following:

Ethylene glycol mono-methyl ether Ethylene glycol mono-ethyl ether Ethylene glycol mono-butyl ether Diethylene glycol mono-methyl ether Diethylene glycol mono-ethyl ether Diethylene glycol mono-butyl ether Triethylene glycol mono-methyl ether Triethylene glycol mono-ethyl ether Tetraethylene glycol di-methyl ether Polypropylene glycol monoalkyl ethers Polypropylene glycol di-alkyl ethers Oxygenated organic compounds of the class enumerated may be dissolved in oil mixtures or solutions which con tain incompatible additive materials for the purpose of minimizing or eliminating said incompatibility. These oxygenated compounds may be added (1) to the base oil before the addition of the polymeric additive or the metallo-organic additive (2) to the oil blend after the addition of either the polymeric additive or the metalloorganic additive (3) to the oil blend after the addition of the polymeric additive and the metallo-organic additive (4) to the metallo-organic additive.

The oxygenated organic compounds are ordinarily used in amounts varying between about 0.001% to 1.0% by weight, preferably 0.006% to 0.3% by weight.

The polymeric additive materials which have utility as viscosity index improvers and pour point depressants and which are found to be incompatible to some degree with the metallo-organic detergent inhibitors are the polymerized or copolymerlzed esters having ester chain lengths within a range of from 8 to 18 carbon atoms in a substantially straight chain. These additive materials are covered by. the term alpha, beta-unsaturated carboxylic acid ester polymers or copolymers. They include, among others, polymers and copolymers of esters of acrylic, methacrylic, crotonic and isocrotonic acid, esters of the dibasic acids, such as, maleic, furnaric, citraconic and mesaconic acid, copolymers of these acid esters with vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl laurate, and the like.

The preparation of these additive materials is accomplished by straightforward methods and present no problem to the art. Examples of the preparation of representative types are set out below.

, PREPARATION OF DI-ALKYL MALEATE ESTER A 3-liter flask equipped with a water trap and a reflux condenser was washed with 294 g. of maleic anhydride, 1118 g. of the alcohol obtained by hydrogenation of coconut oil and containing an average of 13.5 carbon atoms per molecule, 2 g. of sulfosalicylic acid, 400 cc. of xylene, and 200 cc. of naphtha. The above mixture was refluxed for a total of 14 hours, during which time 58 cc. of water were collected. The reaction product was diluted with about 1,000 cc. of benzol and then given four washes with 5% to 10% sodium carbonate solution and two with water. The solvents were removed by evaporation on a ular weight of about 495.

COPOLYMERIZATION OF VINYL ACETATE WITH MALEATE ESTER- A l-liter B-necked flask equipped with a condenser, stirrer, and a thermometer was charged with 200 g. of a lubricating oil having a viscosity at 210 F. of 44 SUS and 300 g. of the maleate ester as prepared above. This mixture was heated to about 30' C. after which it was blown with nitrogen for about minutes. There was then added 4 g. of benzoyl peroxide and the mixture was again blown with nitrogen for about 5 minutes. Vinyl acetate addition was started with stirring about 45 min-' utes after the addition of the benzoyl peroxide and a total of 100 g. of vinyl acetate was added during the course of 1% hours. The reaction mixture was maintained at 80 C. with stirring for 20 hours from the first addition of the vinyl acetate. The resulting copolymer had a viscosity at 210 F. of 3042 SUS.

PREPARATION OF DI-ALKYL FUMARATE-VINYL ACETATE COPOLYMER 650 g. coconut alcohol fumarate (1.31 mols) 113 g. vinyl acetate (1.31 mols) 85 cc. n-heptane 7.63 g. 60-mesh benzoyl peroxide The above charge was stirred for 17 hours minutes at 70 C."under nitrogen atmosphere. n-heptane and unreacted vinyl acetate were removed by evaporation at 80' C. under vacuum. The resulting copolymer product which was water-white and highly viscous. had a molecular weight of about 7,100 Staudinge PREPARATION OF POLYMERIZED ACRYLATE AND ME'I'HACRY lA'I'E'ESTERS r The esters of acrylicv and methacrylic acid are simply prepared by an ester interchange reaction using the desired alcohol, a C C alcohol, and the methyl esters of the acids. Usually an acidic catalyst is used to promote the interchange. Polymers of the esters are prepared by heating the esters to a temperature for about hours at about 100 C. in the presence of a small amount of benzoyl peroxide catalyst. Any unreacted ester may be removed by heating the product in a vacuum (0.5-1 mm.

Hg) to a temperature just above the boiling point of the ester. The polymers obtained are usually colorless or faintly yellow.

The polymeric additive materials having viscosity index improving or pour point depressing properties are blended into lubricating oils in amounts between about 0.02% to 10% by weight, preferably 0.1% to 5.0%, percentages being by weight, based 'on the weight of the total composition.

The metallo-organic additive material having the desirable detergency-improving characteristics are preferably the metal salts of alkylated phenols, metal salts of sulfided alkyl phenol, or the reaction products of the metal salts of sulfided alkyl phenols and phosphorus sulfide. With these materials may be combined a minor amount of a petroleum sulfonate such as calcium petroleum sulfonate, calcium mahogany soaps, metal salts of compounds containing both sulfur and phosphorus, and

4 particularly useful either alone 'or reacted with PllOS- phorus sulfide. These materials are well known in the art of their preparation and are described in detail in United States Patents Nos. 2,362,291 and 2,409,686. It 'has been found that oil compositions containing from a 0.2% to 3.0% by weight of these detergent inhibitors,

based on the weight of the total composition, have desirable detergent properties. A preferred range is from 0.8% to 2% by weight. v

To summarize briefly, the oil compositions of this invention consist essentially of a mineral lubricating oil containing combined therein (1) a copolymer material which imparts desirable properties of viscosity index improving and/or pour depression to the blend, (2) a metallo-organic additive which is useful for improving the detergency characteristic of the oil blend, and (3) a compatibility improver which serves to minimize or eliminate any turbidity caused by a mixture of the metalloorganic additive and the copolymeric material.

In order to more explicitly define the invention 'outlined above, the following examples are given, it being understood that these examples are only illustrative of the inventive concept and not considered to be limiting in any way. Example I A solvent extracted Mid-Continent parafiinic oil having a Saybolt viscosity of 46 seconds at 210 F. and a viscosity index of 110 had added thereto 0.2% of an alkyl maleate-vinyl acetate copolymer prepared according to Ten separate samples of the technique outlined above. the above lubricating oil composition were set aside. To five of these samples were added 0.8% of five separate samples of inhibitor-detergents,consisting of the barium salt of alkyl phenol sulfide reacted with phosphorus sulfide. All five blends were hazy or turbid initially and on several days standing, all blends were very turbid with a precipitate settling out in one blend. To the remaining five samples were added the same inhibitor-detergent additives but in this case the inhibitor-detergent additives contained diethylene glycol monoethyl ether (suflicient 5 quantities to give a concentration of 0.02% in the final 5 blend). After standing two and a half months, the latter aexception, that a different alkyl dibasic acid ester-vinyl acetate copolymer was employed. The blend without the compatibility improver turned cloudy immediately, but

the like. The barium salt of the alkyl phenol sulfide is the blend containing the diethylene glycol mono-ethyl ether (0.02% in final blend) was still clear at the end of the two and a half months examination period.

Example Ill Two samples were prepared as in Example II except that inthe one blend 0.04% diethylene glycol mono-ethyl ether was added directly to the oil blend before the addition of the detergent additive instead of as a component of the latter additive. The blend without the compatibility improver was cloudy immediately, whereas the blend containing the .diethylene glycol mono-ethyl ether was still clear at the end of two and a half months.

Example IV Example III was repeated except that a different sample of alkyl dibasic acid ester-vinyl ester copolymer was employed and 0.02% instead of 0.04% compatibility improver was employed. Results were identical with thom observed in Example III.

Example V Eight oil blends were prepared using the same test oil and the same polyester copolymer (0.2%) described in Example I. To four of the blends were added 2.0% of 4 separate samples of the detergent inhibitor employed in Example I plus calcium petroleum sulfonate. All four blends exhibited some haziness in one day. To the remaining four samples were added the same inhibitor-detergent additives, but in this case the latter additives contained diethylene glycol mono-ethyl ether sumcient to give a final blend concentration of 0.025%. All of the latter blends were clear after two and a half months standing. 1

described in Example VIII. To one of the blends was added 0.04% dimethoxytetraethylene glycol. The blend without the compatibility improver was cloudy initially, whereas the latter blend was clear initially but showed a slight haze at the end of a 40-day low temperature (40 F.) storage test.

The results of the above experiments may be summarized as follows:

COMPATIBILITY OF POLYESTER COPOLYMERB WITH METALLO-ORGANIC ADDI'IIVES [Blends containiil.2% eopolymer in extracted Mid-Continer ig 111 1:51: 5 a Baybolt viscosity oi seconds at 210 F. and a viscosity A cc of Blend A cs 0! Detergent Additive (WPfiout Compatibility Compatibility Improver B1855 Containing Improver) Compatibility Improver 0.8% Metal salt oi alkyl phenol snlfide-i-phos- 'Iurbid initially; precipitate 0.02% Diethylena glycol Clear and oi 2% home sulfide. on standing. mono-ethyl ether. months.

0, m an"; or alkyl phenol sumde-l-phoe- Haze initially; very turbid ..--.do All clear end of horns sulfide (4 samples in several days. 2}?)months.

1.6% Metal salt of alky phenol sulfide Blight haze in one week 0.006% lgliethgglene glycol o.

. mon0-e y e or. Mm] salt or alkyl phenol sulfide Slight haze in several days; -do Clear and of 2% 'c (Indy-2 wks. months.

2.0% Metal salt of alkyl phenol sulnde+phoe- Slight haze initially 0.025% Dlethylene glycol All clear end of phon c )eulflde+calclum mahogany soap (4 mono-ethyl ether. monthssam es 0.8% filetal salt oi alkyl phenol sulfide-l-phos- Tnrbld initially; very turbid 0.04% Methoxy triglycol Clear and cl 2% phorus sulfide. on standing. 7 months.

1) do 0027 Methoxy triglycol- Do.

Do n 0.04% Dimethoxytetraeth- Clear initially! ylene glycol.

m Cloudy initially 0.02% iethylene glycol Clear end of 2% mono-ethyl ether. months.

me do 0.04% Diethylene glycol Do.

mono-ethyl ether.

'Dn n 0.02% Diethylene glycol Do.

mono-ethyl ether.

1 Compatibility improver added directly to oil blend. I Blight haze at and ot soday low temperature (40 F.) storage test.

Example VI Two oil blends were prepared using the same test oil and the same polyester eopolymer (0.2%) described in Example I. To one blend was added 1.0% of a detergent-inhibitor comprising the metal salt of alkylated phenol sulfide and to the second blend was added 1.0% of the same additive containing diethylene glycol monoethyl ether (0.006% concentration in final blend). The first blend exhibited a slight haze in one week, whereas the blend containing the compatibility improver was clear at the end of two and a half months.

Example VII Two oil blends were prepared using the same test oil and the same polyester copolymer (0.2%) described in Example I. To one blend was added 0.8% of calcium isooctyl phenol sulfide and to the second blend was added 0.8% of the same additive containing diethylene glycol mono-ethyl ether (0.006% concentration in final blend). The first blend exhibited a haze in several days and was cloudy in 2 weeks, whereas the blend containing the compatibility improver was clear at the end of two and a half months.

Example VIII half months.

Example IX 1W0 blends were prepared using the same base stock,

An examination of the data appearing in the table above points out the efiicacy of the compatibility improver of this invention. In all instances, the initial turbidity was removed by the addition of minor amounts of the oxygenated compound as defined above.

The compatibility improvers of this invention also have the desirable feature of eliminating the depreciation of the pour point depressing potency which has been experienced when these polymeric additive materials are compounded in a base oil with the detergent-inhibitor additives. The desirable elimination of this loss in pour point depressing potency is illustrated by the following:

Example X Using as a lubricating oil base a highly refined Mid- Continent distillate of SAE 20 grade there was prepared a composition containing 0.02 wt. percent of a copolymer of 80% Lorol B rumarate and 20% vinyl acetate prepared as described above. The ASTM pour point of the blend was '25 F. To enhance the detergent inhibiting properties of this blend, there was added 5% by weight of a blend of calcium cetyl phenate which contained a small amount of sulfurized paraffin and a minor amount of zinc dialkyldithiophosphate. The pour point of the resulting composition was increased 30 to +5 F. This composition was entirely unsuited for low temperature use. The second composition was prepared containing identical amounts of polymeric additive and the detergent-inhibitor and in addition 0.05% by weight of diethylene glycol mono-ethyl ether. The ASTM pour point of this blend was 2S F. clearly showing the utility of the oxygenated organic compound.

Example XI To a highly refined Mid-Continent distillate of SAE 20 grade there was added 0.2 wt. percent of a poly merized methacrylate ester having an ester chain length of between 8 and 18 carbon atoms. The ASTM pour point of this blend was 30 F. A blend containing same polyester copolymer and same detergent additive the same weight percent of the polymethacrylate ester Y 7 in the same base stock and containing in addition wt. percent of the detergent-inhibitor described in Example X above had an ASTM of F. A second blend containing identical amounts of the polymerized meth acrylate ester and the detergent-inhibitor in the same base stock was prepared and in addition 0.05% by weight of a diethylene glycol mono-ethyl ether was added. The ASTM pour point of this final composition was -30" F., pointing out that in this instance, like in Example 291 above, the depreciation of the pour point depressing" potency of the polymerized methacrylate ester by the detergent inhibitor was removed.

To summarize briefly, this invention relates to an oil composition which consists essentially of a mineral lubrieating oil from 0.5% to 10% of a polymerized alpha, beta-unsaturated carboxylic acid ester containing 3 to 18 carbon atoms in the ester portion thereof and cm polymers of such esters with vinyl esters, from 0.2 to 3.0% of a metallic salt of an alkylated phenol, a metallic salt of a sulfided alkylated phenol or the phosphorus sulfide reaction product of such metallic salts, and from 001% to 1.0% of a compatibility improver having the formula:

wherein R is an alkyl group containing from 1 to 8 carbon atoms, R is hydrogen or an alkyl group containing from 1 to 8 carbon atoms and n is an integer from 1 to 8.

The preferred embodiment contemplates the use of a copolymer of a dibasic acid ester containing from 10 to 16 carbon atoms in the ester portion thereof, with a vinyl ester, the barium. salt of an alkylated phenol sulfide, and a diethylene glycol ether.

This is a division of application Serial No. 285,531, filed May 1, 1952, now abandoned, for the same inventors.

What is claimed is:

1. A non-turbid lubricating oil blend having a high having combined therein about 0.05% to about 10.0% by weight of a copolymer of a fumarate ester containing from about 8 to 18 carbon atoms in the ester portion thereof and vinyl acetate, from about 0.2% to about 3.0% by weight of a metal salt of an alkylated phenol as a detergent inhibitor, and from about 0.01% to about 1.0% by weight of a compatibility improver of the class consistr in 16 carbon atoms in the ester portion thereof and vinyl acetate, from about 0.08% to about 2.0% by weight of a metal salt of an alkylated phenol as a detergent inirihltor, and from about 0.06% to about 0.30% by weight of a. compatibility improver of the class of diethylene glycol monoethyl ether, methoxy triglycol, and dimethoxy tetraethylene glycol.

3. A lubricating oil blend according to claim 2 wherein the compatibility improver is diethylene glycol monoethyl ether.

4. A lubricating oil blend according to claim 2 wherein the compatibility improver is methoxy triglycol.

5. A lubricating oil blend according to claim 2 wherein the compatibility improver is dimethoxy tetraethylene glycol.

kelereneescltedinthefileofthlspatent UNITED STATES PATENTS 2,091,627 Bruson Aug. 31, 1937 2,122,593 StafiOrd July 5, 1938 2,123,641 Weizevich July 12, 1938 2,281,623 Schott May 5, 1942 2,338,522 Liberthson Jan. 4, 1944 2,370,080 Schreiber Feb. 20, 1945 2,602,048 Michaels et al July 1, 1952 2,666,746 Munday et al Jan. 19, 1954 

1. A NON-TURBID LUBRICATING OIL BLEND HAVING A HIGH VISCOSITY INDEX AND EXHIBITING A HIGH DEGREE OF DETERGENCY CONSISTING ESSENTIALLY OF A BLEND OF A MINERAL OIL BASE STOCK HAVING COMBINED THEREIN ABOUT 0.05% TO ABOUT 10.0% BY WEIGHT OF A COPOLYMER OF A FUMARATE ESTER CONTAINING FROM ABOUT 8 TO 18 CARBON ATOMS IN THE ESTER PORTION THEREOF AND VINYL ACETATE, FROM ABOUT 0.2% TO ABOUT 3.0% BY WEIGHT OF A METAL SALT OF AN ALKYLATED PHENOL AS A DETERGENT INHIBITOR, AND FROM ABOUT 0.01% TO ABOUT 1.0% BY WEIGHT OF A COMPATIBILITY IMPROVER OF THE CLASS CONSISTING OF DIETHYLENE GLYCOL MONOETHYL ETHER, METHOXY TRIGLYCOL, AND DIMETHOXY TETRAETHYLENE GLYCOL. 